The present invention relates to a single mode pulsed dye laser oscillator.
In the laser art, there is an ever increasing requirement for higher power efficiency capabilities (ratio of power out to power in). There are also ever increasing requirements for smaller and more compact design of single mode pulsed dye lasers. There are several problems inherent in attempting to achieve the combination of higher power efficiency and more compact design.
One problem with single mode pulsed dye lasers is that increasing applied power creates multiple mode outputs rather than single mode selection as desired.
Consequently, it becomes difficult to design a single mode pulsed dye laser oscillator with increased power efficiency capabilities while at the same time reducing the overall physical dimensions and maintaining operation within a narrow bandwidth (e.g., single mode operation).
In an article published in Applied Physics in 1981 entitled "Design Criteria and Operating Characteristics of a Single Mode Pulsed Dye Laser," there is described therein a dye laser which utilizes a combination of a diffraction grating, an etalon, a beam expander, a dye cell and an output mirror in combination. That dye laser is pumped by a 6 KHz copper vapor laser to produce up to 230 mW average power at over five percent efficiency when converting pump energy into a high quality, single mode output beam. The cavity dimensions of that dye laser are approximately 202 mm.
The laser described in the Applied Physics article includes a multi-prism beam expander wherein four prisms are utilized. While the approach described in the Applied Physics article aids in reducing the size of the physical dimensions of the laser itself, nevertheless there are certain inherent limitations with a four prism approach, particularly with respect to reducing the cavity dimensions.
Alternative beam expander capabilities are known in the prior art wherein one, two or more prisms are arranged to provide for beam expansion. For instance, U.S. Pat. No. 4,016,504 describes a multiple prism beam expander wherein a pair of prisms of substantially the same size are positioned relative to one another to provide a magnification factor of approximately twenty. However, the dimensions illustrated in the '504 patent are comparatively large, with cavity dimensions of 180 mm.